accurate length Guaginging device

[zia]

hi friends
I want to make an intelligent device that can measure length of thin object from 5mm to 1000mm.
as i can not use ultrasonic because object is very thin or varnier caliper (as due to its length).
i am thinking such thing which tell me distance travelled by it.
please suggest me sensor(as i have great doubts on accelerometr for distance calculation).
advance thanks
Zia

 

[wp100]

Hi,

Why not make a large vernier type gauge with a screw thread and stepper motor controlled by a micro which will convert the number of steps into mm and output them to a lcd or similar; same basic as one axis of a cnc machine.

 

[zia]

i want to make it so small as well as portable.

 

[PA3040]

As wp100 said, you can simply use screwed variable resister and out put connect to ADC of any MCU

 

[zia]

variable frequency based measurement is more more accurate then this but i want to make device small as well easy like simple roller.